In most metalworking processes, the use of a metalworking fluid is necessary in order to achieve the desired result such as lubrication, cooling, fines removal, etc. Examples of the processes in which these fluids are used include, but are not limited to can making (such as draw and ironing), metal rolling, (such as of aluminum or steel sheets) and punching, sheet bending, etc.
Typically, the processes include the recirculation of spent fluid from the metalworking process through a filtration and equilibration system to remove metal fines, tramp oil, soils, etc. and return the fluid to the metalworking process.
One such system is shown in FIG. 1.
The metalworking station 1 is connected to a sump 2 which collects the spent metalworking fluid. From the sump 2, the fluid is pumped via a conduit 3 to a filtration system 4. The filtration system 4 is comprised of a dirty side 5 and a clean side 6. The coolant is pumped from the dirty side 5 through a filter 7 such as a pleated paper filter, to the clean side 6. The coolant is then pumped via a second conduit 8, to the metalworking process, such as a can making machine.
The fluid concentration is maintained by either adding a premixed supply of fluid or by bulk feeding concentrate of the fluid to the filtration system, generally on the dirty side. Such a supply is shown as 9 in FIG. 1.
This system requires the use of an excessive concentration of fluid in the filtration system. Additionally, the need to maintain high concentrations of the fluid due to losses in the filtration system causes the emulsification of greater amounts of tramp oil and the retention of soils and fines that leads to the premature clogging and replacement of the filter media or cleaning of the filtration system. Moreover, in can making and other metal part manufacture, the higher concentration of fluid causes the fluid, soils and tramp oil to be retained on the finished metal part and the associated tooling which then requires increased cleaning. Lastly, the higher concentration of fluid increases the emulsification level which makes waste more difficult.